This kind of seems like saying 'the more microservices you add, the more useful it gets' which only works up to the point where services don't encounter any integration issues.
What happens when your thermometer starts sending messages that cause your door to unlock when the temperature gets too high? Or if your TV ends up shutting down because of malformed packets being sent across your home network?
IoT is an integration nightmare that only gets worse as stuff fades out or ends up receiving no more support from the manufacturer. Those items you bought from 50 years ago will still work just fine even if the company goes under. But the same can't be said for modern technology we're filling our homes with.
And that's even without talking about the privacy issues. I'll take dumb items that I can make smart over smart items I can not make dumb any day of the week.